Open Access
Control strategy for a droop-controlled grid-connected DFIG wind turbine
(IEEE, 2022) Oraa Iribarren, Iker; Samanes Pascual, Javier; López Taberna, Jesús; Gubía Villabona, Eugenio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
The application of droop control techniques without inner current control loops to doubly-fed induction generator (DFIG) based wind turbines does not allow to provide a stable response at all operating points in terms of rotational speed and active and reactive power. After modeling the system dynamics and analyzing the causes of instability, this paper proposes a control strategy that allows to stabilize the system response at all possible operating points. Simulation results performed in MATLAB/Simulink validate the proposed control strategy proving its effectiveness.
Open Access
Control design and stability analysis of power converters: the discrete generalized Bode criterion
(IEEE, 2021) Urtasun Erburu, Andoni; Samanes Pascual, Javier; Barrios Rípodas, Ernesto; Sanchis Gúrpide, Pablo; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
For the controller design and stability analysis of power electronic converters, the Bode stability criterion and its subsequent revisions are the most practical tools. However, even though the control of the power converter is usually implemented in a microprocessor, none of these methods is infallible when applied to a discrete system. This article therefore proposes a new stability criterion, named the Discrete Generalized Bode Criterion (DGBC). This method is based on the Nyquist criterion but developed from the open-loop Bode diagram, evaluated also at 0 Hz and at the Nyquist frequency. The proposed criterion combines the advantages of the Nyquist and Bode criteria, since it is always applicable and provides an interesting and useful tool for the controller design process. The method is applied to design an active damping control of an inverter with LCL filter, showing how the proposed criterion accurately predicts stability, in contrast to the existing Bode criteria. The theoretical analysis is validated through experimental results performed with a three-phase inverter and an LCL filter.
Open Access
Dual-stage control strategy for a three-level neutral point clamped converter with selective harmonic mitigation PWM
(IEEE, 2023-11-01) Rosado Galparsoro, Leyre; Norambuena, Margarita; Samanes Pascual, Javier; Lezana, Pablo; Gubía Villabona, Eugenio; López Taberna, Jesús; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Grid-connected converters must meet the requirements imposed by grid codes, such as harmonic emission limits and grid voltage support during voltage dips. Selective harmonic mitigation pulsewidth modulation (SHMPWM) is a very interesting technique for high power converters to meet the maximum harmonic emission levels, while keeping a low switching frequency. However, the combination of this modulation with a proportional integral (PI) controller requires slow dynamics, which makes it difficult to comply with the dynamic response requirements of grid codes. As an alternative, model predictive control (MPC) offers a very fast dynamic response, but a wide spread harmonic spectrum in steady state. Thus, the combination of MPC with a PI controller with SHMPWM is advantageous. In this work, a dual-stage control strategy is implemented. During transients, finite control set MPC (FCS-MPC) is activated to rapidly drive the current to the desired reference, while in steady state, the PI controller with SHMPWM is used. Therefore, the dual-stage control strategy allows to comply with the two requirements of grid codes, becoming a suitable strategy for grid-connected converters.
Open Access
Role of student associations in the acquisition of competences in university engineering programs
(IEEE, 2023) Samanes Pascual, Javier; Parra Laita, Íñigo de la; Berrueta Irigoyen, Alberto; Rosado Galparsoro, Leyre; Soto Cabria, Adrián; Elizondo Martínez, David; Catalán Ros, Leyre; Sanchis Gúrpide, Pablo; Institute of Smart Cities - ISC
Students in the STEM field (Science, Technology, Engineering and Mathematics), do not only require deep technical knowledge, but a complete set of global skills related to management, teamwork, lifelong learning, personal development, communications skills or proactiveness, abilities often referred as soft-skills. Student-led organizations, and specifically, university student associations, are one of the best alternatives to promote the acquisition of soft-skills in STEM high education fields. These skills are competences already included in official university programs that can hardly be addressed or acquired from traditional university education. This article studies how student enrollment in student led organizations (SLOs), with an active participation on their organization and activities, allows engineering students to achieve a better development of these soft skills. As case study, a medium size university, with 9000-students and eleven SLOs, six of them focused on STEM related fields, is used in this paper. A survey is conducted among the university community to identify their degree of participation in SLOs, and to test whether participation in these initiatives increases students' self-perception of their soft skill acquisition during their university studies. This survey shows how students of engineering programs, with a high degree of involvement in SLOs, demonstrated greater confidence in their soft skills at the end of their university years.
Open Access
Modeling a grid-forming DFIG wind turbine
(IEEE, 2023-08-31) Oraa Iribarren, Iker; Samanes Pascual, Javier; López Taberna, Jesús; Gubía Villabona, Eugenio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This paper presents a small-signal state-space model that allows analyzing the dynamics of doubly-fed induction generator (DFIG)-based wind turbines in which grid-forming control strategies are implemented. Specifically, in this paper, a droop-controlled DFIG wind turbine is modeled. The system is modeled in the dq-axis, synchronized with the grid voltage, which simplifies the modeling by not having to linearize the terms dependent on the rotational speed of the dq-axis. Independent models for each element of the system are obtained, which are then combined to model the complete system under study. This modeling methodology provides great flexibility, allowing for easy inclusion of the LC harmonic filter, and enabling future incorporation of the grid-side converter to analyze its interaction with the rotor-side converter. The developed model is validated through simulation, demonstrating that it accurately reproduces the dynamic response of the system under study.
Open Access
Deadbeat voltage control for a grid-forming power converter with LCL filter
(IEEE, 2023) Samanes Pascual, Javier; Rosado Galparsoro, Leyre; Gubía Villabona, Eugenio; López Taberna, Jesús; Pérez, Marcelo A.; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Grid-forming power converters are controlled as voltage sources to regulate the grid voltage and frequency. These converters can increase power system strength if they impose a voltage waveform resilient to grid transients. For this reason, in this paper, we propose a deadbeat control strategy of the capacitor voltage for high power converters with LCL filter. To damp the LCL resonant poles, an active damping strategy is developed, based on a modification of the deadbeat control law. With this purpose, a notch filter is applied to the electrical variables allowing to emulate different damping resistances for the fundamental component and the harmonics. As a result, the active damping does not introduce tracking errors of the fundamental frequency component, while it provides damping to the filter resonance. The proposed strategy does not require knowledge of the grid impedance, an interesting feature in grid-connected power converters because the grid impedance is generally unknown. Experimental results validate the proposed strategy.
Open Access
Robust active damping strategy for DFIG wind turbines
(IEEE, 2021) Rosado Galparsoro, Leyre; Samanes Pascual, Javier; Gubía Villabona, Eugenio; López Taberna, Jesús; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Doubly fed induction generators (DFIGs) with an LCL filter are widely used for wind power generation. In these energy conversion systems, there is an interaction between the grid-side converter (GSC) and the rotor-side converter (RSC) control loops, the generator and the LCL filter that must be properly modeled. Such interaction between the GSC and the RSC proves to have a significant influence on the stability. Several active damping (AD) methods for grid-connected converters with an LCL filter have been proposed, nevertheless, the application of these techniques to a DFIG wind turbine is not straightforward, as revealed in this article. To achieve a robust damping irrespective of the grid inductance, this article proposes an AD strategy based on the capacitor current feedback and the adjustment of the control delays to emulate a virtual impedance, in parallel with the filter capacitor, with a dominant resistive component in the range of possible resonance frequencies. This work also proves that, by applying the AD strategy in both converters simultaneously, the damping of the system resonant poles is maximized when a specific value of the grid inductance is considered. Experimental results show the interaction between the GSC and the RSC and validate the proposed AD strategy. © 1986-2012 IEEE.
Open Access
Building global competencies: a strategic approach to internationalization of engineering education
(Eindhoven University of Technology and Fontys University of Applied Sciences, 2023) Berrueta Irigoyen, Alberto; Samanes Pascual, Javier; Parra Laita, Íñigo de la; Goicoechea Fernández, Javier; Sanchis Gúrpide, Pablo; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
International mobility is an essential aspect of undergraduate education that enables students to acquire the necessary competences required by the European Higher Education Area (EHEA). However, small universities such as the Public University of Navarre (UPNA), which has approximately 9,000 bachelor's students, face challenges in providing effective mobility opportunities. The most significant hurdles include offering attractive mobility experiences to students and establishing mobility agreements with other universities. Nonetheless, the reduced size of UPNA provides some potential benefits, such as more personalized advice for students and better knowledge of the available destinations. This article discusses the internationalization strategy implemented by the Faculty of Industrial and ICT Engineering at UPNA, which has enabled over 25% of its students to participate in a mobility experience, resulting in a high satisfaction rate. This contribution provides valuable insights into how smaller universities can successfully offer international mobility programmes to their students.
Open Access
Common-mode and phase-to-ground voltage reduction in back-to-back power converters with discontinuous PWM
(IEEE, 2020) Samanes Pascual, Javier; Gubía Villabona, Eugenio; Juankorena Saldias, Xabier; Gironés Remírez, Carlos; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Discontinuous space vector pulsewidth modulation (DSVPWM) techniques are an interesting option for three-phase, two-level power converters when efficiency is a key factor. Such is the case of back-to-back (B2B) power converters used mainly in wind energy conversion systems and electrical drives. The application of DSVPWMs to B2B converters increases the common-mode (CM) and phase-to-ground (PG) voltages by 50%, compared to conventional space vector pulsewidth modulation (SVPWM7). Higher CM and PG voltages cause bearing currents and insulation stress, which reduce system reliability. In this article, this problem is addressed and two DSVPWM strategies are presented to reduce the CM and PG voltages in B2B power converters. In the first proposal, the CM and PG are both limited to the same values as the conventional SVPWM7 without introducing additional commutations. In the second proposal, a further modification is added to reduce the CM by 50%, compared to the SVPWM7, although this modulation strategy eventually requires two additional commutations in certain periods. Experimental and simulation results validate the performance of the proposed strategies.
Open Access
Modeling of a droop-controlled grid-connected DFIG wind turbine
(IEEE, 2022) Oraa Iribarren, Iker; Samanes Pascual, Javier; López Taberna, Jesús; Gubía Villabona, Eugenio; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Traditionally, to characterize the response of droop-controlled systems RMS models have been used. However, as it is demonstrated in this work, when droop control is applied to doubly-fed induction generators, RMS models do not allow to predict the system stability and dynamic response. Thus, in this article, a linearized small-signal model that overcomes the limitations of RMS models is presented. The proposed model is validated by simulation in MATLAB/Simulink demonstrating that it allows to accurately analyze the stability and dynamic response of the system under study. This model is an interesting tool that can be used in future works to design and adjust grid-forming controllers for doubly-fed induction generators.